Gas-fired barbecues, which grill food, particularly meat, using a propane-fuelled burner to heat a layer of lava rocks beneath the food-supporting grill, have universally replaced the charcoal barbecue as the preferred form of outdoor cooking. Lava rock has been preferred as the heat transferring medium since it simulates the effect of charcoal briquettes in that grease dripping off the cooking meat flares up when it strikes the hot rocks, imparting a desired smoked flavour to the meat. However the use of lava rock also carries with it certain disadvantages. Since the lava rocks are porous and irregular, they do not transfer heat efficiently or evenly to the food being grilled, and therefore such barbecues are not fuel efficient. Grease accumulates in the pores of the lava rocks and flares up, burning the meat. To avoid burning the meat, therefore, the lid of the barbecue is left open to reduce the internal temperature, but causing greater heat loss. Grease drippings penetrate through to the gas burners, causing corrosion and reducing the life of the burners. There may also be a safety problem in that grease is able to leak through to the burner area or even the vicinity the propane tank, accumulates and may ignite. A further problem with lava rock is that it must be replaced periodically, and is difficult to dispose of.
Various attempts have been made to solve the foregoing problems with lava rock. U.S. Pat. No. 4,276,869, Kern, discloses a solid ceramic slab which is positioned between the burner and the food-supporting grate. The slab simulates a bed of coals or briquettes and catches the grease drippings and prevents them from flowing over the edges of the slab. U.S. Pat. No. 4,403,597, Miller, discloses a solid cast iron plate which is positioned between the burner and the food-supporting grate. The plate also simulates a lava bed or charcoal and catches the grease drippings but permits the grease to flow through apertures in the plate onto the burners.
U.S. Pat. No. 4,683,867, Beatty, discloses a gas-fired barbecue which utilizes two rectangular metal plates positioned between the burner and the food-supporting grate to prevent the pooling of grease which might cause a fire. The two plates are overlapping and inclined outwardly at a sufficient angle to cause the grease to flow quickly to flanges at the outside edges of the housing and then off the corners of the plates into circular depressions and a drainage channel which carries the grease to a collecting cup or can. Since the grease still collects at various points within the barbecue, the safety problem is still not overcome by this design.
U.S. Pat. No. 4,773,319, Holland, discloses a barbecue grill which includes a grease collection and drainage system which is positioned between the food-supporting grate and a heat deflector plate above the burner. The grease collector has an inclined central channel which carries the grease to a drainage conduit and then out of the enclosure. Finally, U.S. Pat. No. 5,111,803, Barker et al., discloses a flare reduction buffer, which is a solid cast iron plate which is positioned between the burner and the food-supporting grate. The plate has an array of pockets which are provided with perforations which permit the flow of air and block most food drippings but permit some grease to flow through the plate onto the burners.